In general, a gas cylinder implemented to a chair mainly includes a base tube and a gas spindle, and the height of a seat of the chair is adjusted by up and down movement of the spindle of the gas cylinder.
FIG. 13 is a schematic cross-sectional view showing a structure of a conventional gas cylinder 10.
Referring to FIG. 13, the conventional gas cylinder 10 includes a spindle 13 connected to a bottom surface of a seat of a chair, a base tube 11 supporting the spindle 13, and a tube guide 12 inserted between the base tube 11 and the spindle 13 and preventing left or right sloping of the spindle 13 when the spindle 13 rises or descends.
In detail, the conventional gas cylinder 10 includes a piston 23 performing a relative up and down reciprocating motion in the spindle 13, a piston rod 22 on which the piston 23 is mounted, and a cylinder 16 which is inserted into an inner circumferential surface of the spindle 13 and a surface of which contacts a surface of an O-ring mounted in an outer circumferential surface of the piston 23. Here, the cylinder 16 is divided into an upper chamber 20 and a lower chamber 21 by the piston 23.
Furthermore, the conventional gas cylinder 10 includes a gas sealant 24 sealing a bottom portion of the cylinder 16, a pipe holder 17 sealing an upper portion of the cylinder 16, an open and close pin 15 inserted into the pipe holder 17 by penetrating through a center of the pipe holder 17, and an open pin 14 adjusting the opening and closing of the open and close pin 15 via an up and down motion.
In detail, an orifice 18, through which gas is introduced, is formed on a side of the pipe holder 17, and the orifice 18 is opened and closed by the open and close pin 15. Also, a gas flow channel 19, through which gas discharged through the orifice 18 flows, is formed between the cylinder 16 and the spindle 13.
Hereinafter, an example of a process in which a user sits on a chair will be described to describe functions of the conventional gas cylinder 10 having this structure.
First, the open pin 14 is pressed when the user raises or lowers an operational lever (not shown) connected to the open pin 14 when the user sits on the chair. When the open pin 14 is pressed downwards, the open and close pin 15 descends. When the open and close pin 15 descends, gas stored in the upper chamber 20 flows to the orifice 18 along a side surface of the open and close pin 15. Nitrogen gas having flowed to the orifice 18 flows to the lower chamber 21 through the gas flow channel 19. Then, a volume of the lower chamber 21 becomes greater than a volume of the upper chamber 21 so that the spindle 13 descends. When the force that the user applies to the operational lever is eliminated, no more gas flows. Thus, the chair is fixed at a height desired by the user.
Information disclosed in this Background section was already known to the inventors of the present invention before achieving the present invention or is technical information acquired in the process of achieving the present invention. Therefore, it may contain information that does not form the prior art that is already known to the public in this country.